On the Categories search widget I’ve tried to change the focus color from that yellowish-brown to the following:

#extended-categories-select-2:focus {
border: 1px solid #14B37D;
}

It adds the color on top of the yellowish-brown.

I’m assuming it’s :focus because in firebug I’m choosing :focus from the Toggle Element State selector and that’s what shows up, but when implement the css above it doesn’t change the color it adds it on top of the yellowish-brown.